What Is the Origin of the Calendar?
The modern calendar borrows influences from a collective of early calendars such as the Jewish, the Babylonian, the Roman, and the Egyptian calendars.
by Mike Cohen
thecollector.com/what-is-the-o…
Books on calendars at PG:
gutenberg.org/ebooks/subject/2…
Maya calendar:
gutenberg.org/ebooks/subject/1…